package com.hns.tool.pub;

/**
 * Created by xieyanghe on 16/3/14.
 */
public class GpsCorrect {

    final static double pi = 3.14159265358979324;
    final static double a = 6378245.0;
    final static double ee = 0.00669342162296594323;

    /**
     * 地球坐标系(WGS-84)转火星坐标系(CGJ-02)
     * @param wgLat
     * @param wgLon
     * @return
     */
    public static double[] transform(double wgLat, double wgLon) {

        double[] result = {-1,-1};

        if (outOfChina(wgLat, wgLon)) {

            result[0] = wgLat;
            result[1] = wgLon;

        }else{

            double dLat = transformLat(wgLon - 105.0, wgLat - 35.0);
            double dLon = transformLon(wgLon - 105.0, wgLat - 35.0);
            double radLat = wgLat / 180.0 * pi;
            double magic = Math.sin(radLat);
            magic = 1 - ee * magic * magic;
            double sqrtMagic = Math.sqrt(magic);
            dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
            dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
            result[0] = wgLat + dLat;
            result[1] = wgLon + dLon;
        }

        return result;
    }

    private static boolean outOfChina(double lat, double lon) {
        if (lon < 72.004 || lon > 137.8347)
            return true;
        if (lat < 0.8293 || lat > 55.8271)
            return true;
        return false;
    }

    private static double transformLat(double x, double y) {

        double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
        ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
        ret += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
        return ret;
    }

    private static double transformLon(double x, double y) {
        double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
        ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
        ret += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0 * pi)) * 2.0 / 3.0;
        return ret;
    }

    /**
     * 火星坐标系(CGJ-02)转地球坐标系(WGS-84)
     * @param wgLat
     * @param wgLon
     */
    public static double[] gcj2wgs(double wgLat, double wgLon){

        double[] result = {-1,-1};

        double latitude = wgLat - (transform(wgLat, wgLon)[0] - wgLat);
        double lontitude = wgLon - (transform(wgLat, wgLon)[1] - wgLon);

        result[0] = latitude;
        result[1] = lontitude;

        return result;
    }
}
